Tohoku J. Exp. Med., 2001, 193 (1)

Isolated and Focal Retrograde Amnesia;
A Hiatus in the Past

ATSUSHI YAMADORI, KYOKO SUZUKI, MASUMI SHIMADA, TAKASHI TSUKIURA, TAKAHIRO MORISHIMA and TOSHIKATSU FUJII

Division of Neuropsychology, Department of Disability Medicine Tohoku University Graduate School of Medicine, Sendai 980-8575

Two cases of isolated retrograde amnesia were reported. Both showed the same clinical pattern in development and resolution of amnesia despite of different etiologies. Sudden insult to the brain (trauma in Case 1 and viral encephalitis in Case 2) caused concurrent antero- and retrograde amnesia. Fortunately both recovered from the anterograde amnesia completely. However, both were left with a period of postictal amnesia of a few months and retrograde amnesia of up to 14 months' duration. The analysis of their pattern of temporal evolution and dissolution of amnesia support the hypothesis that recently acquired episodic information requires a certain amount of constant activation for a certain period of time in order to be organized into a durable memory. The nature of this activation as well as its origin remains to be solved.

Keywords —— isolated retrograde amnesia; anterograde amnesia; postictal amnesia; memory trace; memory activation

© 2001 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2001, 193, 57-65

Address for reprints: Atsushi Yamadori, Division of Neuropsychology, Department of Disability Medicine, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Boba-ku, Sendai 980-8575, Japan.

e-mail: yamadori@mail.cc.tohoku.ac.jp